Long‐Lasting Moisture Energy Scavenging in Dry Ambient Air Empowered by a Salt Concentration‐Gradient Cationic Hydrogel

Abstract Converting ambient moisture into electric power is attractive as a next‐generation energy harvesting technology, serving as a countermeasure to overwhelming energy demands due to its sustainability and ubiquitous nature. However, achieving a long‐lasting and high density of electrical power generation at low humidity is challenging. Here, synergizing a water flow and an auxiliary anion migration in tandem with an embedded ion flow in a salt concentration‐gradient cationic gel, these challenges are tackled and developed a moisture‐activated electricity generator (MEG) with longevity (>50 days), low energy loss, and adequate power of 13.8 mW m ⁻² at low (30%) relative humidity. Witha stacking strategy with combinations of serial and parallel configurations, the electrical output of the MEG module can cover practical electric devices with a broad range of power consumption, unveiling the potential of MEG to power practical appliances sustainably and omnipresently.